Fig. 1: S. cochlearispathum inflorescence, showing spathe and spadix characteristic for the Araceae family. Scale bar: 2 cm.
© Waheed Arshad, 2013
Species in the Spathiphyllum genus are members of the monocotyledonous flowering plant family Araceae, often called the arum or aroid family. They are native to tropical regions of the Americas, and southeastern Asia, most commonly in lowland forests where they are closely associated with streams1.
S. cochlearispathum, Liebm. is one of the largest species in the genus, growing to around 80 cm (31.5 inches) in height. As evergreen herbaceous perennials, certain species in the genus are very commonly sold as house plants, a large number as hybridised “Peace Lilies”. This common name is actually somewhat confusing, given the genus does not belong to the true lily (Liliaceae) family!1
In fact, the taxonomy of the aroid family is rather difficult; a close relationship between the Araceae and various aquatic monocotyledonous families (e.g. Alismataceae) has previously been suggested, mainly on morphological evidence2, and has now been supported by molecular data3. However, the gross morphological characters used in the most recent revision4 of Spathiphyllum require more detailed examination1. Typically, Spathiphyllum spp. are terrestrial, herbaceous plants with creeping rhizomes, making the plant look almost acaulous (without a stem). There are several leaves present per plant – often with fully-sheathed petioles – and moderately numerous lateral veins extending to the margins.
The solitary inflorescence deserves more careful observation. Interestingly, the word Spathiphyllum comes from the Greek for leaf-spathe, which refers to the large sheathing bract enclosing the spike of minute flowers, and, later, the fruit (Fig. 1, above). The fleshy axis (spadix), around which the spathe is arranged, forms the inflorescence which is typical for members of the Araceae family. It is precisely this remarkable form that makes these plants so popular, particularly as the spathe can be elaborately coloured. Closer, microscopic observations would reveal that the numerous, ebracteate flowers are bisexual with four to six perianth segments (calyx and corolla whorls, indistinguishable).
Fig. 2: Hybridised Spathiphyllum on sale in Morrisons, Reading, with the (incorrectly-spelled) label enlarged.
© Waheed Arshad, 2013
Many of us commonly grow a “Peace Lily” in our homes, so may have some knowledge of its growing habit (Fig. 2). The majority of Spathiphyllum spp. today originated from the 1800s, when collectors in South America sought “new” and “interesting” plants suitable for indoor growing in Europe… and interesting too it is! The “Peace Lily” is often reported to be a very useful houseplant – with documented research highlighting the air-cleansing capacities of the plant. One recent study5 provided the first comprehensive demonstration of the ability of such a system to act as a biofilter, removing airborne contaminants such as benzene and n-hexane (in a process known as phytoremediation). In fact, Spathiphyllum spp. have been known to have this capability since the National Aeronautics and Space Administration (NASA) conducted their Clean Air Study in 1989! This indoor filtering microcosm may indeed offer many phytoremediating advantages over physical and chemical methods, including being more sustainable and cost-economising in the long term!
So cleaning air and beautifying the indoor environment…? Pause and admire that “Peace Lily” on the mantlepiece, because a house-plant doesn’t get much more useful than that!
References:
1. Cardona, F. (2004) Synopsis of the genus Spathiphyllum (Araceae) in Colombia. Annals of the Missouri Botanical Garden 91 (3): 448–456.
2. Dahlgren, R.M.T., Clifford, H.T. and Yeo, P.F. (1985) The Families of the Monocotyledons. Berlin, Springer-Verlag.
3. Chase, M.W., Fay, M.F., Devey, D.S., Maurin, O., Rønsted, N., Davies, T.J., Pillon, Y., Petersen, G., Seberg, O., Tamura, M.N., Asmussen, C.B., Hilu, K., Borsch, T., Davis, J.I., Stevenson, D.W., Pires, J.C., Givnish, T.J., Sytsma, K.J., McPherson, M.A., Graham, S.W. and Rai, H.S. (2006) Multi-gene Analyses of Monocot Relationships: A Summary. In: Colombus, J.T., Friar, E.A., Hamilton, C.W., Porter, J.M., Prince, L.M. and Simpson, M.G. (eds.), Monocots: Comparative Biology and Evolution. Rancho Santa Ana Botanic Garden, Claremont, California, USA.
4. Bunting, G.S. (1960) A revision of Spathiphyllum (Araceae). Memoirs of the New York Botanical Garden 10 (3): 1–53.
5. Wood, R.A., Orwell, R.L., Tarran, J., Torpy, F. and Burchett, M. (2002) Potted-plant / growth media interactions and capacities for removal of volatiles from indoor air. Journal of Horticultural Science and Biotechnology 77 (1): 120–129.
